A method includes forming a first transistor, a second transistor, a third transistor, and a fourth transistor over a substrate, wherein at least the second and third transistors include ferroelectric materials; forming an interlayer dielectric (ILD) layer over the first to fourth transistors; forming a first metal line over the ILD layer to interconnect drains of the second and third transistors and a gate of the fourth transistor; forming a second metal line over the ILD layer to interconnect a drain of the first transistor and gates of the second and third transistors; forming a write word line over the ILD layer and electrically connected to a gate of the first transistor but electrically isolated from the fourth transistor; forming a word line over the ILD layer and electrically connected to a source of the first transistor; and forming a bit line electrically connected to the fourth transistor.

A method includes depositing a high-k gate dielectric layer over and along sidewalls of a semiconductor fin. The method further includes depositing an n-type work function metal layer over the high-k gate dielectric layer and performing a passivation treatment on the high-k gate dielectric layer through the n-type work function metal layer. The passivation treatment comprises a remote plasma process. The method further includes depositing a fill metal over the n-type work function metal layer to form a metal gate stack over the high-k gate dielectric layer. The metal gate stack comprising the n-type work function metal layer and the fill metal.

A method includes forming a semiconductor fin protruding higher than top surfaces of isolation regions. The isolation regions extend into a semiconductor substrate. The method further includes etching a portion of the semiconductor fin to form a trench, filling the trench with a first dielectric material, wherein the first dielectric material has a first bandgap, and performing a recessing process to recess the first dielectric material. A recess is formed between opposing portions of the isolation regions. The recess is filled with a second dielectric material. The first dielectric material and the second dielectric material in combination form an additional isolation region. The second dielectric material has a second bandgap smaller than the first bandgap.

A device includes a substrate, an isolation structure over the substrate, and two fins extending from the substrate and above the isolation structure. Two source/drain structures are over the two fins respectively and being side by side along a first direction generally perpendicular to a lengthwise direction of the two fins from a top view . Each of the two source/drain structures has a near-vertical side, the two near-vertical sides facing each other along the first direction. A contact etch stop layer (CESL) is disposed on at least a lower portion of the near-vertical side of each of the two source/drain structures. And two contacts are disposed over the two source/drain structures, respectively, and over the CESL.

A method of forming a semiconductor device includes: forming a fin protruding above a substrate; forming a gate layer over the fin; and patterning the gate layer in a plasma etching tool using a plasma etching process to form a gate over the fin, where patterning the gate layer includes: turning on and off a top radio frequency (RF) source of the plasma etching tool alternately during the plasma etching process; and turning on and off a bottom RF source of the plasma etching tool alternately during the plasma etching process, where there is a timing offset between first time instants when the top RF source is turned on and respective second time instants when the bottom RF source is turned on.

A method according to the present disclosure includes depositing, over a substrate, a stack including channel layers interleaved by sacrificial layers, forming a first fin structure and a second fin in a first area and a second area of the substrate, depositing a first dummy gate stack over the first fin structure and a second dummy gate stack over the second fin structure, recessing source/drain regions of the first fin structure and second fin structure to form first source/drain trenches and second source/drain trenches, selectively and partially etching the sacrificial layers to form first inner spacer recesses and second inner spacer recesses, forming first inner spacer features in the first inner spacer recesses, and forming second inner spacer features in the second inner spacer recesses. A composition of the first inner spacer features is different from a composition of the second inner spacer features.

A method includes providing a substrate, a dummy fin, and a stack of semiconductor channel layers; forming an interfacial layer wrapping around each of the semiconductor channel layers; depositing a high-k dielectric layer, wherein a first portion of the high-k dielectric layer over the interfacial layer is spaced away from a second portion of the high-k dielectric layer on sidewalls of the dummy fin by a first distance; depositing a first dielectric layer over the dummy fin and over the semiconductor channel layers, wherein a merge-critical-dimension of the first dielectric layer is greater than the first distance thereby causing the first dielectric layer to be deposited in a space between the dummy fin and a topmost layer of the stack of semiconductor channel layers, thereby providing air gaps between adjacent layers of the stack of semiconductor channel layers and between the dummy fin and the stack of semiconductor channel layers.

Sub-fin isolation schemes for gate-all-around (GAA) transistor devices are provided herein. In some cases, the sub-fin isolation schemes include forming one or more dielectric layers between each of the source/drain regions and the substrate. In some such cases, the one or more dielectric layers include material native to the gate sidewall spacers, for example, or other dielectric material. In other cases, the sub-fin isolation schemes include substrate modification that results in oppositely-type doped semiconductor material under each of the source/drain regions and in the sub-fin. The oppositely-type doped semiconductor material results in the interface between that material and each of the source/drain regions being a p-n or n-p junction to block the flow of carriers through the sub-fin. The various sub-fin isolation schemes described herein enable better short channel characteristics for GAA transistors (e.g., employing one or more nanowires, nanoribbons, or nanosheets), thereby improving device performance.

A method for manufacturing a semiconductor device includes forming a gate trench over a semiconductor fin, the gate trench including an upper portion and a lower portion. The method includes sequentially forming one or more work function layers, a capping layer, and a glue layer over the gate trench. The glue layer includes a first sub-layer and a second sub-layer that have respective different etching rates with respect to an etching solution. The method includes removing the second sub-layer while leaving a first portion of the first sub-layer filled in the lower portion of the gate trench.

Semiconductor devices and manufacturing and design methods thereof are disclosed. In one embodiment, a semiconductor device includes an active FinFET disposed over a workpiece comprising a first semiconductive material, the active FinFET comprising a first fin. An electrically inactive FinFET structure is disposed over the workpiece proximate the active FinFET, the electrically inactive FinFET comprising a second fin. A second semiconductive material is disposed between the first fin and the second fin.